Soulseek is a resource hog
Soulseek crashes
Soulseek's server is down sometimes.
Soulseek does not have multi-source downloading.
Soulseek often has some form of bug going on that makes you have to check the dudes blog to see whats going on.
Yet it's the only p2p I use for music, and I've tried a bunch for a long time now.
This goes to show that a good community makes the client, far more then the quality of the client itself. The music selection for me is simply unparalleled on Soulseek, and I'm not some electronic freak. Soulseeks' community is excellent for anything outside of the top 40 charts.
I imagine this is the future of p2p music, not waste or kazaa. Clients that connect you to, say 10,000-70,000 others who have tastes you share, not 50-300 others (like waste or direct connect) and not a million others (like kazaa) who you can't really connect to and are all sharing the latest 50 cent and the paris hilton video only.
Just my opinion, of course.